Compressor assembly having dynamic diffuser ring retention

ABSTRACT

A compressor assembly is disclosed. The compressor assembly may have a compressor housing, which may have an inner wall inclined at a first angle relative to a plane disposed generally orthogonal to a rotational axis of the compressor assembly. The compressor assembly may also have a compressor impeller disposed within the compressor housing. Further, the compressor assembly may have a bearing housing attached to the compressor housing. The bearing housing may have a body portion and a web that may extend outward from the body portion to a web end. The web may be inclined at a second angle relative to the plane. The compressor assembly may have a diffuser ring disposed between the inner wall and the web. The compressor assembly may also have a spring disposed between the web and the diffuser ring. The spring may be configured to apply a generally axial load on the diffuser ring.

TECHNICAL FIELD

The present disclosure relates generally to a compressor assembly and, more particularly, to a compressor assembly having dynamic diffuser ring retention.

BACKGROUND

Internal combustion engines, for example, diesel engines, gasoline engines, or natural gas engines employ turbochargers to deliver compressed air for combustion in the engine. A turbocharger compresses air flowing into the engine, helping to force more air into combustion chambers of the engine. The increased supply of air allows for increased fuel combustion in the combustion chambers, resulting in increased power output from the engine.

A typical turbocharger includes a shaft, a turbine wheel connected to one end of the shaft, a compressor wheel connected to the other end of the shaft, and bearings to support the shaft. Separate housings connected to each other enclose the compressor wheel, the turbine wheel, and the bearings. Exhaust from the engine expands over the turbine wheel and rotates the turbine wheel. The turbine wheel in turn rotates the compressor wheel via the shaft. The compressor wheel receives cool air from the ambient and forces compressed air into combustion chambers of the engine.

The compressor stage of a turbocharger often includes a diffuser configured to reduce the speed of the air leaving the compressor wheel. Reducing the air speed causes the air pressure within the compressor stage to increase, which in turn helps to deliver compressed air to the combustion chambers of the engine. The compressor diffuser usually includes vanes extending between the bearing housing and the compressor housing. These vanes direct the spinning air from the compressor impeller into the compressor housing volute. Because the compressor housing, the compressor diffuser, and the bearing housing are subject to different and varying temperatures, these components expand and contract to different extents, causing gaps to develop between the tips of the vanes and the compressor housing inner walls. Leakage of air through these gaps can significantly reduce compressor performance.

One attempt to address some of the problems described above is disclosed in U.S. Pat. No. 6,168,375 of LaRue et al. that issued on Jan. 2, 2001 (“the '375 patent”). In particular, the '375 patent discloses a turbocharger with a radial flow compressor having an annular vane diffuser disposed within the compressor housing. The vane diffuser of the '375 patent is positioned within a channel in an axially-facing surface of a compressor housing back plate. The vane diffuser of the '375 patent is also supported at one end by a lip on the back plate and on the other end by a portion of the compressor housing. The '375 patent further discloses a wave-type compression spring interposed between the vane diffuser and the axially-facing back plate to urge the vanes against the wall of the compressor housing forming one side of the diffuser. The '375 patent also discloses that during turbocharger operation, static pressure within the compressor housing volute bleeds back behind the vane diffuser to urge the vane diffuser axially away from the back plate, helping to keep the vanes in contact with the housing. In addition, the '375 patent discloses that the wave spring imposes a pressure load onto the vane diffuser to urge it axially away from the back plate regardless of static pressure conditions. Further, the '375 patent discloses an annular seal disposed within a seal groove formed in the axially-facing back plate surface. The seal of the '375 patent is interposed between the vane diffuser and the back plate and reduces recirculation of air around the backside surface of the vane diffuser.

Although the '375 patent discloses a spring-loaded diffuser, the disclosed diffuser may still not be optimal. For example, the disclosed spring-loaded diffuser design may not be useable in a mixed flow turbocharger that does not have a back plate having axially facing portions. The disclosed diffuser also may not have sufficient room for radial expansion during operation of the turbocharger because the diffuser of the '375 patent is radially constrained by the back plate lip and the compressor housing. Additionally, because the wave spring and the seal of the '375 patent are disposed on the same axially-facing back plate surface, the wave spring may push the diffuser axially away from the back plate surface, reducing the effectiveness of the seal and allowing recirculation of air around the back plate. Further still, the diffuser of the '375 patent requires machining of a channel to accommodate the spring on the axially-facing back plate surface. The need for a machined channel for the spring may increase the manufacturing cost of the compressor assembly of the '375 patent.

The compressor assembly of the present disclosure solves one or more of the problems set forth above and/or other problems of the prior art.

SUMMARY

In one aspect, the present disclosure is directed to a compressor assembly. The compressor assembly may include a compressor housing. The compressor housing may include an inner wall inclined at a first angle relative to a plane disposed generally orthogonal to a rotational axis of the compressor assembly. The compressor assembly may also include a compressor impeller disposed within the compressor housing. Further, the compressor assembly may include a bearing housing attached to the compressor housing. The bearing housing may include a body portion and a web. The web may extend outward from the body portion to a web end. The web may be inclined at a second angle relative to the plane. The compressor assembly may also include a diffuser ring disposed between the inner wall and the web. In addition, the compressor assembly may include a spring disposed between the web and the diffuser ring. The spring may be configured to apply a generally axial load on the diffuser ring.

In another aspect, the present disclosure is directed to a diffuser ring. The diffuser ring may include a back plate. The back plate may include a front face inclined at a first angle relative to a plane disposed generally orthogonal to a rotational axis. The back plate may also include a rear face inclined at a second angle relative to the plane. Further the back plate may include a top face extending axially from the front face towards the rear face. In addition, the back plate may include a bottom face extending axially from the front face towards the rear face. The diffuser ring may also include a vane extending outward from the front face.

In yet another aspect, the present disclosure is directed to a turbocharger. The turbocharger may include a turbine housing. The turbocharger may also include a turbine wheel disposed within the turbine housing and configured to be driven by exhaust received from an engine. Further, the turbocharger may include a compressor housing. The compressor housing may include an inner wall inclined at a first angle relative to a plane disposed generally orthogonal to a rotational axis of the turbocharger. The turbocharger may also include a compressor impeller disposed within the compressor housing. The turbocharger may include a shaft connecting the turbine wheel and the compressor impeller. In addition, the turbocharger may include a bearing housing attached to the compressor housing and the turbine housing. The bearing housing may include a body portion and a web. The web may extend outward from the body portion to a web end. The web end may be inclined at a second angle relative to the plane. The turbocharger may further include a diffuser ring disposed between the inner wall and the web. The turbocharger may also include a spring disposed between the web and the diffuser ring, the spring being configured to apply a generally axial load on the diffuser ring.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cut-away view of an exemplary disclosed turbocharger;

FIG. 2 is a cut-away view of an exemplary disclosed compressor assembly for the turbocharger of FIG. 1;

FIG. 3 is a another cut-away view of the exemplary disclosed compressor assembly for the turbocharger of FIG. 1;

FIG. 4 is a pictorial view of a portion of the exemplary disclosed compressor assembly of FIG. 2;

FIG. 5 is a cut-away view of an exemplary disclosed turbocharger cartridge for the turbocharger of FIG. 1;

FIG. 6 is a cut-away view of an exemplary disclosed compressor housing assembly for the turbocharger of FIG. 1;

FIG. 7 is a pictorial illustration of an exemplary disclosed clamping plate for the compressor housing assembly of FIG. 6 or the turbine housing assembly of FIG. 8; and

FIG. 8 is a cut-away view of an exemplary disclosed turbine housing assembly for the turbocharger of FIG. 1.

DETAILED DESCRIPTION

FIG. 1 illustrates an exemplary embodiment of a turbocharger 10. Turbocharger 10 may be used with an engine (not shown) of a machine that performs some type of operation associated with an industry such as mining, construction, farming, railroad, marine, power generation, or another industry known in the art. As shown in FIG. 1, turbocharger 10 may include compressor stage 12 and turbine stage 14. Compressor stage 12 may embody a fixed geometry compressor impeller 16 attached to a shaft 18. Compressor impeller 16 may include compressor hub 20 that may extend from hub front end 22 to hub rear end 24. Compressor blades 26 may be disposed on compressor hub 20 between hub front end 22 and hub rear end 24 in one or more rows. In one exemplary embodiment as illustrated in FIG. 1, compressor impeller 16 may include first row 28, second row 30, and third row 32 of compressor blades 26. First row 28 of compressor blades 26 may be disposed adjacent hub front end 22. Third row 32 of compressor blades 26 may be disposed adjacent hub rear end 24. Second row 30 of compressor blades 26 may be disposed in between first and third rows 28, 32 of compressor blades 26. Third row 32 of compressor blades 26 may be a rearmost row 32, which may be located closest to hub rear end 24 as compared to first row 30 or second row 32. Although FIG. 1 illustrates only three rows (first row 28, second row 30, and third row 32) of compressor blades 26, it is contemplated that compressor impeller 16 may include any number of rows 28, 30 of compressor blades 26. Turbine stage 14 may include a turbine wheel 34, which may also be attached to shaft 18. Turbine wheel 34 may include turbine hub 36 and turbine blades 38 disposed around turbine hub 36.

Compressor stage 12 may be enclosed by compressor housing 40. Turbine stage 14 may be enclosed by turbine housing 42. Bearing housing 44 may enclose bearings (not shown) that may support shaft 18. Bearing housing 44 may be attached to compressor housing 40 via bolts 46. Likewise, bearing housing 44 may be attached to turbine housing 42 via bolts 48. Compressor impeller 16, shaft 18, turbine wheel 34, compressor housing 40, turbine housing 42, and bearing housing 44 may be disposed around rotational axis 50 of turbocharger 10.

Exhaust gases exiting the engine (not shown) may enter turbine housing 42 via turbine inlet 52 and exit turbine housing 42 via turbine outlet 54. The hot exhaust gases may move through turbine housing 42, expanding against turbine blades 38, rotating turbine wheel 34. Rotation of turbine wheel 34 may rotate shaft 18, which in turn may rotate compressor impeller 16. Air may enter compressor housing 40 via compressor inlet 56 and exit compressor housing 40 via compressor outlet 58. As air moves through compressor stage 12, compressor impeller 16 may spin and accelerate the air. Compressor stage 12 may include diffuser ring 60, which may help slow down the air, causing an increase in the pressure of the air within compressor stage 12. Compressed air from compressor stage 12 may be directed into the engine.

As further illustrated in FIG. 1, compressor housing 40 may extend from compressor front end 62 to compressor rear end 64. Compressor housing 40 may include intake portion 66, transition portion 68, diffuser portion 70, and volute 72. Intake portion 66 may extend from adjacent compressor front end 62 to first distal end 74 disposed between compressor front end 62 and compressor rear end 64. In one exemplary embodiment as illustrated in FIG. 1, first distal end 74 may be disposed adjacent hub front end 22 of compressor impeller 16. Intake portion 66 may have a generally frusto-conical shape, which may help direct air from the ambient into compressor housing 40. It is contemplated, however, that intake portion 66 may have a generally cylindrical or any other type of shape known in the art. Transition portion 68 of compressor housing 40 may extend from first distal end 74 to second distal end 76 disposed between first distal end 74 and compressor rear end 64. In one exemplary embodiment as illustrated in FIG. 1, second distal end 76 may be disposed adjacent outer edge 78 of third row 32 of compressor blades 26. As illustrated in FIG. 1, transition portion 68 may have an inner surface 80 that may be radially separated from outer edges 78 of compressor blades 26 in first, second, and third rows 28, 30, 32 by a radial gap 82. Diffuser portion 70 may extend from second distal end 76 to third distal end 84, which may be disposed adjacent volute 72. Volute 72 may have a generally toroidal shape and may be disposed around rotational axis 50. Volute 72 may be connected to diffuser portion 70 at third distal end 84. Intake portion 66, transition portion 68, and diffuser portion 70 may help direct air from compressor inlet 56 to volute 72 during operation of turbocharger 10.

FIG. 2 illustrates a cut-away view of an exemplary embodiment of compressor assembly 90 of turbocharger 10. As illustrated in FIG. 2, volute 72 may have a volute inner surface 92 that may extend from third distal end 84 to fourth distal end 94. In one exemplary embodiment as illustrated in FIG. 2, volute inner surface 92 may have a generally circular cross-section. Fourth distal end 94 may be axially spaced apart from third distal end 84 in a direction towards compressor rear end 64. Volute 72 may be bounded by diffuser portion wall 96, volute top wall 98, and volute rear wall 100. Volute rear wall 100 may be axially separated from diffuser portion wall 96. Volute top wall 98 may connect diffuser portion wall 96 and volute rear wall 100 to form a continuous and smooth volute inner surface 92.

As also illustrated in FIG. 2, bearing housing 44 may include body portion 102, web 104, and bearing housing flange 106. Body portion 102 of bearing housing 44 may be disposed symmetrically around rotational axis 50. Web 104 may extend outward from body portion 102 to web end 108. In one exemplary embodiment as illustrated in FIG. 2, web end 108 may be disposed adjacent fourth distal end 94 and volute rear wall 100. Web end 108 may have a radius “R₁,” which may be larger than a radius “R₂” of outer edge 78 of third row 32 of compressor blades 26. As also illustrated in FIG. 2, for example, web 104 may be generally inclined at an angle θ₁ relative to an axial plane disposed generally orthogonal to rotational axis 50. One of ordinary skill in the art would recognize that surfaces inclined at an angle relative to an axial plane disposed generally orthogonal to rotational axis 50 would correspondingly be inclined relative to rotational axis 50.

Bearing housing flange 106 may extend radially outward from web end 108 to bearing housing flange end 110. In one exemplary embodiment as illustrated in FIG. 2, bearing housing flange 106 may be disposed generally orthogonal to rotational axis 50. Bearing housing flange 106 may have flange front face 112 and a flange rear face 114 disposed opposite to flange front face 112. Bearing housing flange 106 may also have a generally cylindrical flange outer surface 116, which may have a radius “R₃,” which may be larger than radius R₁ of web end 108. Flange front face 112 may be disposed adjacent to and may abut on rear face 118 of volute rear wall 100.

Bearing housing flange 106 may also include a flange recess 120, which may extend axially inwards from flange front face 112 towards flange rear face 114. Flange recess 120 may extend radially from adjacent web end 108 to recess outer edge 122. In one exemplary embodiment as illustrated in FIG. 2, recess outer edge 122 may have a radius “R₄,” smaller than radius R₃ of flange outer surface 116. Flange recess 120 may have a recess seating surface 124 disposed axially spaced apart from flange front face 112 and rear face 118 of volute rear wall 100. Recess seating surface 124 may have a generally annular shape and may extend from adjacent web end 108 to adjacent recess outer edge 122. Bearing housing flange 106 may be attached to volute rear wall 100 of compressor housing 40 via one or more bolts 46.

Web 104 may include a first web face 126, ledge 128, and second web face 130. First web face 126 may extend outward from adjacent outer edge 78 of third row 32 to ledge 128 disposed between outer edge 78 and web end 108. First web face 126 may be inclined at an angle “θ₂” relative to an axial plane disposed generally orthogonal to rotational axis 50. First web face 126 may be disposed opposite to and axially spaced apart from inner wall 132 of diffuser portion 70 of compressor housing 40. Inner wall 132 may be inclined at an angle “θ₃” relative to an axial plane disposed generally orthogonal to rotational axis 50. First web face 126 and inner wall 132 may form passageway 134. First web face 126 and inner wall 132 may have a smooth shape that may help ensure that air can travel from outer edges 78 of compressor blades 26 through passageway 134 without significantly altering a velocity or direction of the air. In one exemplary embodiment, first web face 126 may have a smooth curvilinear shape that may conform to a shape of compressor blades 26. Likewise, inner wall 132 may have a smooth curvilinear shape that may conform to a surface defined by outer edges 78 of compressor blades 26 in first, second, and third rows 28, 30, 32.

Ledge 128 may have a generally cylindrical ledge outer surface 136, which may have a radius “R₅” relative to rotational axis 50. Ledge outer surface 136 may extend axially from first web face 126 to ledge end 138 disposed between first web face 126 and compressor rear end 64. Radius R₅ of ledge outer surface 136 may be larger than a radius “R₂” of outer edges 78 of compressor blades 26 in third row 32. Ledge outer surface 136 may also include a generally annular groove 140. Ledge 128 may include ledge axial face 142 that may be axially spaced apart from first web face 126. Ledge axial face 142 may be disposed at ledge end 138. Ledge axial face 142 may extend radially outward from ledge outer surface 136 to second web face 130. In one exemplary embodiment as illustrated in FIG. 2, ledge axial face 142 may intersect second web face 130 at ledge axial face end 144. In one exemplary embodiment as illustrated in FIG. 2, ledge axial face 142 may be disposed generally orthogonal to rotational axis 50. Second web face 130 may extend from ledge axial face end 144 to web end 108. Second web face 130 may be inclined at an angle “θ₄” relative to an axial plane disposed generally orthogonal to rotational axis 50.

Diffuser ring 60 may be disposed between inner wall 132 of compressor housing 40 and second web face 130 of bearing housing 44. Diffuser ring 60 may include back plate 146 and one or more vanes 148. In one exemplary embodiment as illustrated in FIG. 2, back plate 146 may extend from back plate leading edge 150 to back plate trailing edge 152. Back plate 146 may have a generally annular shape. In one exemplary embodiment as illustrated in FIG. 2, back plate leading edge 150 may be disposed adjacent ledge outer surface 136 and back plate trailing edge 152 may be disposed adjacent fourth distal end 94. Back plate 146 may include front face 154, top face 156, bottom face 158, inclined rear face 160, axial rear face 162, and recess 164. Front face 154 of back plate 146 may extend from back plate leading edge 150 to back plate trailing edge 152. Front face 154 may have a generally curvilinear and smooth shape and may be disposed opposite to and axially spaced apart from inner wall 132 of compressor housing 40. Front face 154 may be shaped to help ensure air from passageway 134 may smoothly flow over front face 154.

Top face 156 of back plate 146 may extend axially from front face 154 to axial rear face 162 disposed adjacent recess seating surface 124. Top face 156 may have a generally cylindrical shape. Top face 156 may be disposed adjacent inner face 166 of volute rear wall 100. Inner face 166 of volute rear wall 100 may also have a generally cylindrical shape. Top face 156 of back plate 146 may be radially separated from inner face 166 by a radial gap 168. Bottom face 158 of back plate 146 may extend axially from front face 154 towards inclined rear face 160 disposed adjacent second web face 130. Bottom face 158 may abut on ledge outer surface 136. Bottom face 158 may have a generally cylindrical shape. It is contemplated, however, that bottom face 158 may have a non-cylindrical shape. Seal member 170 may be disposed in groove 140 between ledge outer surface 136 and bottom face 158. In one exemplary embodiment as illustrated in FIG. 2, seal member 170 may be an O-ring. It is contemplated, however, that seal member 170 may be a gasket or any other type of sealing element known in the art. Seal member 170 may prevent recirculation of air around back plate 146.

Axial rear face 162 of back plate 146 may be axially separated from front face 154 of back plate 146. Axial rear face 162 may extend radially inward from top face 156 to adjacent web end 108. Axial rear face 162 may connect top face 156 with inclined rear face 160. In one exemplary embodiment as shown in FIG. 2, axial rear face 162 may be disposed generally orthogonal to rotational axis 50. Inclined rear face 160 may extend from axial rear face 162 adjacent web end 108 to adjacent ledge axial face end 144. Inclined rear face 160 may be inclined at an angle “θ₅” relative to a plane disposed generally orthogonal to rotational axis 50. One of ordinary skill in the art would recognize that inclined rear face 160 would be inclined relative to top face 156 and axial rear face 162. Inclined rear face 160 may be axially separated from front face 154 of back plate 146. Inclined rear face 160 may be disposed adjacent second web face 130. In one exemplary embodiment as illustrated in FIG. 2, inclined rear face 160 may be axially separated from second web face 130 by cavity 172. Seal member 170 may prevent a flow of air from volute 72 to passageway 134 via cavity 172.

Recess 164 may be disposed adjacent bottom face 158 and between bottom face 158 and inclined rear face 160. Recess 164 may include recess upper face 174 and recess side face 176. Recess upper face 174 may have a generally cylindrical shape and may extend axially from inclined rear face 160 towards front face 154. Recess upper face 174 may be radially separated from ledge outer surface 136. In one exemplary embodiment as illustrated in FIG. 2, recess upper face 174 may have a radius “R₆” relative to rotational axis 50. Radius R₆ may be larger than radius R₅ of ledge outer surface 136. Recess side face 176 may extend radially inward from recess upper face 174 to bottom face 158. In one exemplary embodiment, recess side face 176 may have a generally annular shape, which may be disposed generally orthogonal to rotational axis 50. Recess side face 176 may be axially disposed between ledge axial face 142 and front face 154. Recess side face 176 may be axially separated from ledge axial face 142.

Vane 148 may extend radially and axially outward from front face 154 of back plate 146 to vane tip 178. In one exemplary embodiment as illustrated in FIG. 2, vane tip 178 may abut on inner wall 132 of compressor housing 40. Vane 148 may extend from a vane leading edge 180 to a vane trailing edge 182. Vane leading edge 180 may be disposed adjacent back plate leading edge 150. Vane leading edge 180 may intersect front face 154 of back plate 146 at a location which may be offset from back plate leading edge 150. For example, as illustrated in FIG. 2, vane leading edge 180 may intersect front face 154 of back plate 146 at a location disposed between back plate leading edge 150 and back plate trailing edge 152. As illustrated in FIG. 2, vane 148 may extend over a portion of front face 154 of back plate 146 so that vane trailing edge 182 may be offset from back plate trailing edge 152. Thus, for example, a length “L₁” of front face 154 may be larger than a length “L₂” of vane 148. Air from passageway 134 may flow between vanes 148 and enter volute 72. A shape of each vane 148 and a circumferential spacing between vanes 148 may be selected so that vanes 148 may help reduce a speed of the air flowing between vanes 148, thereby helping to increase a pressure of the air in volute 72.

Wave spring 184 may be disposed in recess 164 between ledge axial face 142 and recess side face 176 of recess 164 in back plate 146. Wave spring 184 may have a generally annular shape having an inner radius, which may be larger than a radius R₅ of ledge outer surface 136. Wave spring 184 may include a plurality of waves on axial face 186 of wave spring 184. In one exemplary embodiment, wave spring 184 may have about 11 waves. Wave spring 184 may have an axial thickness ranging from 2 mm to 4 mm. In an assembled configuration as illustrated in the exemplary embodiment of FIG. 2, wave spring 184 may have a thickness ranging from about 1.5 mm to about 2.5 mm. Wave spring 184 may have a spring constant ranging from about 20 to 30 N/mm (Newtons per mm). Wave spring 184 may apply an axial load on back plate 146 to urge vane tips 178 to firmly abut on and remain in contact with inner wall 132 of compressor housing 40. By helping to keep vane tips 178 firmly in contact with inner wall 132, wave spring 184 may help ensure that no appreciable amount of air can leak from passageway 134 into volute 72 via gaps between vane tips 178 and inner wall 132 of compressor housing 40.

As also illustrated in FIG. 2, vanes 148 may be disposed nearer to volute 72 as compared to outer edges 78 of compressor blades 26 so as to define a vaneless space 200. Vaneless space 200 may extend within passageway 134 from outer edges 78 of compressor blades 26 in third row 32 to vane leading edges 180. Vaneless space 200 may have a generally annular shape extending between inner wall 132 of compressor housing 40 and first web face 126 of bearing housing 44. In one exemplary embodiment, a radial extent “AR” of vaneless space 200 between midpoints 202 and 204 may range from about 20% to 40% of a maximum radius R₂ of compressor blades 26.

Vaneless space 200 may be inclined at an angle “θ₆” relative to an axial plane disposed generally orthogonal to rotational axis 50. Angle θ₆ may be measured between an axis 206 of vaneless space 200 and an axial plane disposed generally orthogonal to rotational axis 50. For example, axis 206 of vaneless space 200 may be defined as a line connecting midpoints 202 and 204 of passageway 134. Midpoint 202 may be disposed adjacent an outer edge 78 of compressor blades 26. Midpoint 204 may be disposed adjacent a vane leading edge 180. As used in this disclosure midpoint 202 may be disposed within passageway 134 halfway between inner wall 132 and second web face 130. Similarly, midpoint 204 may be disposed within passageway 134 halfway between inner wall 132 and front face 154 of back plate 146. One of ordinary skill in the art would recognize that axis 206 may not always be disposed parallel to inner wall 132 and/or second web face 130. As also illustrated in FIG. 2, a portion 208 of vaneless space 200 may be disposed between inner wall 132 and second web face 130. A remaining portion 210 of vaneless space 200 may be disposed between inner wall 132 and front face 154 of back plate 146.

The above description refers to angles θ₁, θ₂, θ₃, θ₄, θ₅, and θ₆. It is contemplated that angles θ₁, θ₂, θ₃, θ₄, θ₅, and θ₆ may be equal or unequal. In one exemplary embodiment, each of angles θ₁, θ₂, θ₃, θ₄, θ₅, or θ₆ may range from about 0° to about 45°.

FIG. 3 illustrates another cut-away view of an exemplary embodiment of compressor assembly 90 of turbocharger 10. As illustrated in FIG. 3, volute rear wall 100 may include recess 220, which may extend axially from rear face 118 of volute rear wall 100 towards volute inner surface 92. Volute rear wall 100 may have a thickness “t₁.” Recess 220 may have a depth “t₂,” which may be smaller than thickness t₁. Recess 220 may include recess rear face 222, which may be disposed generally orthogonal to rotational axis 50. Recess rear face 222 may be disposed generally parallel to axial rear face 162 of back plate 146 of diffuser ring 60. Recess 220 may also include recess side surface 224, which may extend axially from rear face 118 of volute rear wall 100 to recess rear face 222.

As illustrated in FIG. 3, back plate 146 of diffuser ring 60 may include one or more tabs 226 disposed circumferentially around back plate 146. A circumferential spacing between tabs 226 may be uniform or non-uniform. Tab 226 may extend radially outward from top face 156. Tab 226 may have a tab front face 228 and a tab rear face 230 disposed opposite tab front face 228. Tab 226 may also have tab side surface 232 extending between tab front face 228 and tab rear face 230. Tab front face 228 may be disposed adjacent to and axially separated from recess rear face 222 by an axial gap 234. Tab side surface 232 may be radially separated from recess side surface 224 by a radial gap 236.

FIG. 4 illustrates a pictorial view of an exemplary embodiment of compressor assembly 90. As illustrated in FIG. 4, tab 226 may span a circumferential angle “φ.” In one exemplary embodiment, angle φ may range from about 5° to 10°. As illustrated in FIG. 4, a first tab 226 may be disposed about a first diametrical axis 237 and a second tab 226 may be disposed about a second diametrical axis 238. In one exemplary embodiment as illustrated in FIG. 4, first diametrical axis 237 may be disposed generally orthogonal to second diametrical axis 238. It is contemplated, however, that first diametrical axis 237 may be disposed at any angle relative to second diametrical axis 238. Further, as illustrated in the exemplary embodiment of FIG. 4, back plate 146 may have about 4 tabs 226. It is contemplated, however, that back plate 146 may have any number of tabs 226. Tabs 226 may engage with recesses 220 in volute rear wall 100. Tabs 226 may be configured to act as anti-rotational features that prevent rotation of back plate 146 around rotational axis 50.

As further illustrated in FIG. 4, volute rear wall 100 may include one or more recesses 239. Recess 239 may have a depth, which may be smaller than depth t₂ of recess 220. Recess 239 may include a hole 240, which may be threaded. Back plate 146 may be attached to volute rear wall 100 by a fastener 242. Fastener 242 may pass through washer 244 and threadingly engage with threads in hole 240. Washer 244 may abut on volute rear wall 100 and axial rear face 162 of diffuser ring 60 to attach diffuser ring 60 to volute rear wall 100. Depths of recesses 220 and 239 may be selected such that tab front face 228 may remain axially separated from recess rear face 222 of volute rear wall 100. In one exemplary embodiment as illustrated in FIG. 4, back plate 146 of diffuser ring 60 may include about four tabs 226. As also illustrated in the exemplary embodiment of FIG. 4, diffuser ring 60 may be attached to volute rear wall 100 using about three washers 244 and three fasteners 242. It is contemplated, however, that any number of washers 244 and fasteners 242 may be used to attach volute rear wall 100 and diffuser ring 60.

Returning to FIG. 3, compressor stage 12 may include shim 246. Shim 246 may have a generally annular shape and may be disposed around rotational axis 50. Shim 246 may have a shim front face 248 disposed adjacent to and abutting on rear face 118 of volute rear wall 100. Shim 246 may also have a shim rear face 250 disposed opposite shim front face 248. Shim rear face 250 may be disposed adjacent to and may abut on recess seating surface 124. In one exemplary embodiment as illustrated in FIG. 3, shim 246 may be attached to bearing housing flange 106 using one or more rivets 252. Rivets 252 may be circumferentially spaced from each other. A circumferential spacing between rivets 252 may be uniform or non-uniform. In one exemplary embodiment a number of rivets 252 may range from about 6 to 12. Although the above description refers to rivets 252, it is contemplated that bolts, screws, or any other types of fasteners known in the art may be used to attach shim 246 to bearing housing flange 106. Shim 246 may be configured to define a space 254 between shim front face 248 and recess seating surface 124. Shim 246 and consequently space 254 may have a thickness “t₃,” which may be selected so that gaps between vane tips 178 and inner wall 132 of compressor housing 40 can be reduced or eliminated after assembly of compressor housing 40 with bearing housing 44.

FIG. 5 illustrates a pictorial view of an exemplary embodiment of turbocharger cartridge 256. As illustrated in FIG. 5, turbocharger cartridge 256 may include compressor impeller 16, shaft 18, turbine wheel 34, turbine housing 42, and bearing housing 44. Dimensional measurements of turbocharger cartridge 256 combined with dimensional tolerances on compressor housing 40 may be used to determine a maximum required thickness t₃ of shim 246. These dimensional measurements and dimensional tolerances may be used to select thickness t₃ of shim 246 so that vane tips 178 may be firmly in contact with inner wall 132 of compressor housing 40 without introducing a gap between vane tips 178 and inner wall 132. Thus, shim 246 and turbocharger cartridge 256 may constitute a matched set. By selecting thickness t₃ of shim 246 in this manner, gaps between vane tips 178 and inner wall 132 may depend only on the dimensional tolerances of compressor housing. In one exemplary embodiment, thickness t₃ may be selected as a maximum thickness that may be required to ensure that vane tips 178 come into contact with inner wall 132 based on the dimensional tolerances of compressor housing 40. In particular, an axial load may be applied to shaft 18, pushing compressor impeller 16 away from turbine housing 42 and towards compressor front end 62. An axial distance “A” between recess seating surface 124 and a gage location 258, on compressor impeller 16, may be measured.

An axial distance “B” (see FIG. 2) may be measured between rear face 118 of volute rear wall 100 and a gage location 259 on inner wall 132 of compressor housing 40. Gage location 259 may be a predetermined location on inner wall 132 of compressor housing 40. In one exemplary embodiment as illustrated in FIG. 2, gage location 259 may be disposed adjacent to gage location 258. Further, a variation in distance B may be determined based on known manufacturing tolerances. Additionally or alternatively, the variation in distance B may be determined based on measurements of distance B on a plurality of compressor housings 40. A maximum thickness t₃ may be determined based on distance A, distance B, and the variation of distance B, so that that vane tips 178 may remain in contact with inner wall 132 of compressor housing 40. For example, thickness t₃ may be selected so that a distance “C” between recess seating surface 124 of bearing housing flange 106 and gage location 259 may be greater than or equal to a sum of thickness t₃ (see FIG. 3) and a maximum value of distance B determined based on the variation in distance B. Shim 246 having the maximum required thickness t₃ may be attached to bearing housing flange 106 of bearing housing 44 in turbocharger cartridge 256. In one exemplary embodiment thickness t₃ of shim 246 may range from about 1.5 mm to about 2.5 mm.

FIG. 6 illustrates a cut-away view of an exemplary embodiment of compressor housing assembly 260 for compressor assembly 90 of turbocharger 10. Compressor housing assembly 260 includes one or more clamping plates 262 and one or more bolts 46 that cooperate to connect compressor housing 40 with bearing housing flange 106 of bearing housing 44. Clamping plate 262 may abut on compressor housing 40 and bearing housing flange 106. In one exemplary embodiment, clamping plate 262 may be a single generally annular plate disposed around rotational axis 50. Clamping plate 262 may have a front face 264 and a rear face 266 disposed opposite to and axially spaced apart from front face 264. A plurality of holes 268 may be disposed on clamping plate 262. Holes 268 may be circumferentially spaced from each other. A circumferential spacing between holes 268 may be uniform or non-uniform. Holes 268 may be through holes that may extend from front face 264 to rear face 266. In some exemplary embodiments, holes 268 may have threads. Clamping plate 262 may have a radial width “W₁.”

Compressor housing 40 may have a compressor housing flange 270 attached to volute top wall 98 and volute rear wall 100. Compressor housing flange 270 may have a generally cylindrical flange outer surface 272. Flange outer surface 272 may have a radius “R₇” relative to rotational axis 50. Compressor housing flange 270 may also include flange inner surface 274, which may have a radius “R₈” relative to rotational axis 50. Radius R₈ may be larger than or about equal to radius R₃ of flange outer surface 116 of bearing housing flange 106. Radius R₈ may also be smaller than radius R₇. Flange inner surface 274 may be disposed adjacent to and may abut on flange outer surface 116 of bearing housing flange 106 of bearing housing 44. Compressor housing flange 270 may include a clamping face 276, which may extend radially from flange inner surface 274 at radius R₈ to flange outer surface 272 at radius R₇. Clamping face 276 may have a radial width “W₂,” which may be smaller than a width W₁ of clamping plate 262.

Clamping face 276 of compressor housing flange 270 may include compressor flange recess 278 and compressor flange lip 280. Compressor flange recess 278 may extend axially inwards from clamping face 276 towards compressor front end 62 forming compressor flange lip 280 on clamping face 276. Compressor flange recess 278 may extend radially outward from flange inner surface 274 to recess outer edge 282 disposed between flange inner surface 274 and flange outer surface 272. Compressor flange recess 278 may have a radial width “W₃,” which may be smaller than a radial width W₂ of clamping face 276. In one exemplary embodiment width W₃ may range from about 70% to about 90% of width W₂. As illustrated in FIG. 6, compressor flange recess 278 may include a recess surface 284 axially spaced apart from clamping face 276 of clamping plate 262. In one exemplary embodiment, an axial spacing of recess surface 284 from clamping face 276 may range from about 0.8 mm to about 1.4 mm. Recess surface 284 may extend radially outward from flange inner surface 274 to recess outer edge 282. Compressor flange lip 280 may be disposed adjacent recess outer edge 282 of compressor flange recess 278. Compressor flange lip 280 may extend radially outward from recess outer edge 282 to flange outer surface 272. As also illustrated in FIG. 6, front face 264 of clamping plate 262 may abut on compressor flange lip 280.

Recess surface 284 of compressor housing flange 270 may include a plurality of holes 286. Like holes 268, holes 286 may be circumferentially spaced from each other. A circumferential spacing between holes 286 may be uniform or non-uniform. Holes 286 may be arranged so as to align with holes 268. Holes 286 may also be threaded. Bolts 46 may pass through holes 268 and may be threadingly received in holes 286 to help connect clamping plate 262 with compressor housing flange 270. In some exemplary embodiments, bolts 46 may be also threadingly received in holes 268. Although FIG. 6 illustrates bolts 46 being assembled with holes 268 and/or holes 286, it is contemplated that threaded studs (not shown) may be threadingly assembled into holes 286 and nuts (not shown) abutting on rear face 266 of clamping plate 262 may be attached to the studs to connect clamping plate 262 to compressor housing flange 270.

Clamping plate 262 may include clamping plate overhang portion 288, which may extend radially inward from adjacent flange inner surface 274. Overhang portion 288 may include a front face portion 290 that may abut on flange rear surface 114 of bearing housing flange 106. As illustrated in FIG. 6, clamping face 276 of compressor housing flange 270 may be disposed generally coplanar with flange rear surface 114 of bearing housing flange 106. As also illustrated in FIG. 6, clamping plate 262 may extend over compressor flange recess 278 and abut on compressor flange lip 280 and flange rear face 114 of bearing housing flange 106. Supporting clamping plate 262 at two radial locations in this manner may help minimize and/or eliminate bending loads transferred by clamping plate 262 to bolts 46. Further, compressor flange recess 278 may permit clamping plate 262 to bend in compressor flange recess 278 between compressor flange lip 280 and bearing housing flange 106, when bolts 46 are turned, helping to generate tensile loads in bolts 46. Tensile loads generated in bolts 46 may in turn help to firmly attach clamping plate 262 to compressor housing flange 270 and bearing housing flange 106.

FIG. 7 illustrates another exemplary embodiment of clamping plate 262, which may have one or more segments. FIG. 7 illustrates a view of clamping plate 262 on a plane disposed generally orthogonal to rotational axis 50. As illustrated in FIG. 7, clamping plate 262 may include first clamping plate segment 292, second clamping plate segment 294, and third clamping plate segment 296. Each of first second and third clamping plate segments 292, 294, 296 may be an annular arc-shaped plates having one or more holes 286. As illustrated in FIG. 7, first, second, and third clamping plate segments 292, 294, 296 may be circumferentially disposed so as to circumscribe rotational axis 50 so that holes 286 may also be circumferentially disposed around rotational axis 50. In one exemplary embodiment as illustrated in FIG. 7, each of first second and third clamping plate segments 292, 294, 296 may include three holes 286 circumferentially spaced equidistant from each other. It is contemplated, however, that each of first second and third clamping plate segments 292, 294, 296 may include any number of holes 286, which may or may not be disposed circumferentially equidistant from each other. Each of first, second, and third clamping plate segments 292, 294, 296 may have an inner radius “R₉” and an outer radius “R₁₀” greater than R₉. It is contemplated, however, that first, second, and third clamping plate segments 292, 294, 296 may have the same or different radii R₉ and R₁₀. Each of first, second, and third clamping plate segments 292, 294, 296 may span a circumferential angle “θ₇.” For example, circumferential angle θ₇ may be an angle between leading edge 298 to trailing edge 300 of first, second, and third clamping segments 292, 294, 296. It is contemplated, however, that first, second, and third clamping plate segments 292, 294, 296 may span the same or different circumferential angles θ₇. Although three clamping plate segments have been illustrated in FIG. 7, it is contemplated that clamping plate 262 may have any number of arc-shaped clamping plate segments 292, 294, 296.

FIG. 8 illustrates a cut-away view of an exemplary embodiment of turbine housing assembly 310 for turbine stage 14 of turbocharger 10. Turbine housing assembly 310 includes one or more clamping plates 312 and one or more bolts 48 that cooperate to connect turbine housing 42 and bearing housing 44. Clamping plate 312 may abut on turbine housing 42 and bearing housing 44. In one exemplary embodiment, clamping plate 312 may be a single generally annular plate disposed around rotational axis 50. It is contemplated, however, that like clamping plate 262, clamping plate 312 may also have one or more segments similar to first clamping plate segment 292, second clamping plate segment 294, and third clamping plate segment 296. It is also contemplated that clamping plate 262 may have a first plurality of clamping plate segments and clamping plate 312 may have a second plurality of clamping plate segments. It is further contemplated that a number of clamping plate segments of clamping plate 262 may be the same as or different from a number of clamping plate segments of clamping plate 312. In addition, it is contemplated that clamping plate 312 may have a thickness, which may be the same as or different from a thickness of clamping plate 262. Clamping plate 312 may have a front face 314 and a rear face 316 disposed opposite to and axially spaced apart from front face 314. A plurality of holes 318 may be disposed on clamping plate 312. Holes 318 may be circumferentially spaced from each other. A circumferential spacing between holes 318 may be uniform or non-uniform. Holes 318 may be through holes that may extend from front face 314 to rear face 316. In some exemplary embodiments, holes 318 may have threads. Clamping plate 312 may have a radial width “W₄.”

Turbine housing 42 may have a turbine housing wall 320. Turbine housing wall 320 may include a notch 322. Notch 322 may have a notch inner surface 324 and a notch rear wall 326. Notch inner surface 324 may have a generally cylindrical shape disposed around rotational axis 50. Notch rear wall 326 may extend radially inward from notch inner surface 324 and may be disposed generally orthogonal to rotational axis 50. Turbine housing wall 320 may also include turbine inner surface 328, which may enclose turbine wheel 34 (see FIG. 1). In addition, turbine housing wall may include clamping face 330 disposed opposite the turbine inner surface 328. Clamping face 330 may extend radially outward from notch inner surface 324 to turbine wall outer end 332.

Clamping face 330 of turbine housing wall 320 may include turbine flange recess 334 and turbine wall lip 336. Turbine flange recess 334 may extend axially inwards from clamping face 330 towards turbine inner surface 328 forming turbine wall lip 336. Turbine flange recess 334 may extend radially outward from notch inner surface 324 to recess outer edge 338 disposed between notch inner surface 324 and turbine wall outer end 332. Turbine flange recess 334 may have a radial width “W₅,” which may be smaller than a radial width W₄ of clamping plate 312. In one exemplary embodiment radial width W₅ may range from about 70% to about 90% of width W₄. As illustrated in FIG. 8, turbine flange recess 334 may include a recess surface 340 axially spaced apart from clamping face 330 of turbine housing wall 320. In one exemplary embodiment, an axial spacing of recess surface 340 from clamping face 330 may range from about 0.8 mm to about 1.4 mm. Recess surface 340 may extend radially outward from notch inner surface 324 to recess outer edge 338. Turbine wall lip 336 may be disposed adjacent recess outer edge 338 of turbine flange recess 334. Turbine wall lip 336 may extend radially outward from recess outer edge 338 to turbine wall outer end 332. As also illustrated in FIG. 8, rear face 316 of clamping plate 312 may abut on turbine wall lip 336. Recess surface 340 of turbine housing wall 320 may include a plurality of holes 342. Like holes 318, holes 342 may be circumferentially spaced from each other. A circumferential spacing between holes 342 may be uniform or non-uniform. Holes 342 may be arranged so as to align with holes 318. Holes 342 may also be threaded.

Bearing housing 44 may include a bearing housing flange 344. Bearing housing flange 344 may have front face 346, rear face 348 disposed opposite front face 346, and bearing flange outer surface 350. Bearing housing flange 344 may abut on notch rear wall 326 of turbine housing wall 320 such that bearing flange outer surface 350 may be disposed adjacent to and may abut on notch inner surface 324. Clamping plate 312 may include an overhang portion 352, which may extend radially inward from holes 318. Overhang portion 352 may include a rear face portion 354 that may abut on front face 346 of bearing housing flange 344. As illustrated in FIG. 8, clamping face 330 of turbine housing wall 320 may be disposed generally coplanar with front face 346 of bearing housing flange 344.

Bolts 48 may pass through holes 318 and may be threadingly received in holes 342 to help connect clamping plate 312 with turbine housing wall 320 and bearing housing flange 344. In some exemplary embodiments, bolts 48 may be also threadingly received in holes 318. Although FIG. 8 illustrates bolts 48 being assembled with holes 318 and/or holes 342, it is contemplated that threaded studs (not shown) may be threadingly assembled into holes 342 and nuts (not shown) abutting on front face 314 of clamping plate 312 may be attached to the studs to connect clamping plate 312 to turbine housing wall 320. As illustrated in FIG. 8, clamping plate 312 may extend over turbine flange recess 334 and abut on turbine wall lip 336 on turbine housing 42 and front face 346 of bearing housing flange 344. Supporting clamping plate 312 at two radial locations in this manner may help minimize and/or eliminate bending loads transferred by clamping plate 312 on bolts 48. Further, clamping plate 312 may bend within turbine flange recess 334 when bolts 48 are turned, helping to generate tensile load in bolts 48. Tensile loading in bolts 48 may in turn help to firmly attach clamping plate 312 to turbine housing wall 320 and bearing housing flange 344.

INDUSTRIAL APPLICABILITY

The disclosed compressor assembly 90 may be implemented to help reduce or eliminate leakage of air through gaps between vane tips 178 of compressor diffuser ring 60 and inner wall 132 of compressor housing 40. Compressor assembly 90 may also be implemented to help improve an efficiency of compressor stage 12 by using shim 246 dimensionally matched to turbocharger cartridge 256 to help reduce or eliminate gaps between vane tips 178 and inner wall 132. Additionally, compressor assembly 90 may be implemented to reduce or eliminate failure of compressor blades induced by excitation of compressor blades 26 caused by pressure wakes generated by vanes 148 in diffuser ring 60. Further, compressor assembly 90 may be implemented to help ensure that compressor housing 40, bearing housing 44, and turbine housing 42 may be assembled without inducing bending loads on bolts 46, 48. The disclosed compressor assembly 90 may also be implemented help reduce wear on internal components of compressor assembly 90 caused by thermally induced relative movement between the components.

Referring to FIGS. 1 and 2, during operation of turbocharger 10, exhaust gases from the engine (not shown) may enter turbine housing 42 via turbine inlet 52, expand against turbine blades 38, rotating turbine wheel 34. Rotation of turbine wheel 34 may rotate shaft 18, which in turn may rotate compressor impeller 16. Air may enter compressor housing 40 via compressor inlet 56 and exit compressor housing 40 via compressor outlet 58. As air moves through compressor stage 12, the rotating compressor impeller 16 may accelerate the air. Air leaving outer edges 78 of compressor blades 26 may be decelerated as the air flows between vanes 148 of diffuser ring 60. Deceleration of air in diffuser ring 60 may increase a pressure of the air in volute 72 of compressor stage 12. Air compressed by the pressure generated in compressor stage 12 may be forced into the combustions chambers of the engine for combustion of fuel. Air flowing in gaps between inner wall 132 and vane tips 178 can bypass the deceleration induced by diffuser ring 60, reducing the ability of diffuser ring 60 to convert the kinetic energy of the air into pressure in volute 72. Reduced pressure in volute 72 may adversely affect performance of the engine.

Compressor assembly 90 may include numerous features that help to reduce or eliminate gaps between vane tips 178 and inner wall 132 of compressor housing 40. For example, compressor assembly 90 may include a wave spring 184 disposed between second web face 130 and back plate 146 of diffuser ring 60. Wave spring 184 may exert an axial force on back plate 146 forcing diffuser ring 60 to move towards compressor front end 62 and pushing vane tips 178 to firmly come into contact with inner wall 132 of compressor housing 40. By forcing vane tips 178 to firmly abut on inner wall 132, wave spring 184 may help reduce or eliminate gaps between vane tips 178 and inner wall 132 at all operating conditions of turbocharger 10. Wave spring 184 may also help reduce or eliminate damage caused to vanes 148 when the turbocharger is not operational by helping to urge vane tips 178 to come into contact with inner wall 132. Allowing vane tips 178 to remain in contact with inner wall 132 in this manner may help prevent excessive vibration of vanes 148, which in turn may help reduce or eliminate damage to vanes 148.

Furthermore, during operation of turbocharger 10, high pressure air from volute 72 may bleed through radial gap 168 into cavity 172. The high pressure air may help push back plate 146 away from second web face 130 toward compressor front end 62, which in turn may urge vane tips 178 to firmly come into contact with inner wall 132 of compressor housing 40. By forcing vane tips 178 to firmly abut on inner wall 132, bleed air in cavity 172 may help reduce or eliminate gaps between vane tips 178 and inner wall 132 during high pressure operation of compressor stage 12.

Radial gap 168 and seal member 170 may also help back plate 146 of diffuser ring 60 to freely expand thermally during operation of compressor stage 12. For example, diffuser ring 60 may be made of aluminum, aluminum alloy, or other alloys, which has a relatively high coefficient of thermal expansion compared to compressor housing 40 and bearing housing 44, both of which may be made of an iron alloy or other alloys. The radial gap 168 and the compressive nature of seal member 170 may allow back plate 146 to expand without coming into contact with or interfering with inner face 166 of volute rear wall 100 of bearing housing 44. Moreover, because seal member 170 is disposed on ledge outer surface 136, which is disposed generally orthogonal to wave spring 184, the axial force exerted by wave spring 184 may not diminish the compressive forces generated in seal member 170. As a result operation of wave spring 184 may not diminish the strength of the seal generated by seal member 170 between ledge outer surface 136 and bottom face 158 of back plate 146. Consequently, seal member 170 may be able to maintain a very effective seal, preventing recirculation of air from volute 72 through cavity 172 and into passageway 134 during the entire range of operation of turbocharger 10, helping to improve the efficiency of compressor stage 12.

Referring to FIGS. 1-4, compressor assembly 90 may also help reduce or eliminate gaps between vane tips 178 and inner wall 132 of compressor housing 40 by reducing the dimensional mismatch between compressor impeller 16, shaft 18, turbine wheel 34, compressor housing 40, turbine housing 42 and bearing housing 44. In particular, dimensions of turbocharger cartridge 256 may be measured after assembling compressor impeller 16, shaft 18, turbine wheel 34, turbine housing 42, and bearing housing 44. A maximum thickness t₃ of shim 246 may be selected based on the measured dimensions of turbocharger cartridge 256 and dimensional tolerances associated with compressor housing 40. In particular, an axial load may be applied to shaft 18, pushing compressor impeller 16 away from turbine housing 42 and towards compressor front end 62. An axial distance “A” between recess seating surface 124 and a gage location 258, on compressor impeller 16, may be measured. Gage location 258 may be a predetermined location on compressor impeller 16. Further, an axial distance “B” may be measured between rear face 118 of volute rear wall 100 and a gage location 259 on inner wall 132 of compressor housing 40. In addition, a variation of distance B may be determined based on known manufacturing tolerances. Additionally or alternatively, the variation may be determined based on measurements of distance B on a plurality of compressor housings 40. A maximum thickness t₃ may be determined based on distance A, distance B, and the variation of distance B, so that that vane tips 178 may remain in contact with inner wall 132 of compressor housing 40. For example, thickness t₃ may be selected so that a distance “C” between recess seating surface 124 of bearing housing flange 106 and gage location 259 may be greater than or equal to a sum of thickness t₃ and a maximum value of distance B determined based on the variation in distance B. Shim 246 with the selected thickness t₃ may be fixedly attached to bearing housing flange 106. Matching thickness t₃ of shim 246 to turbocharger cartridge 256 in this manner may help ensure that vane tips 178 may firmly abut on inner wall 132 of compressor housing 40 regardless of the dimensional tolerance variations expected in compressor housing 40. Thus, selecting a thickness t₃ for shim 246 matched to turbocharger cartridge 256 may help reduce or eliminate gaps between vane tips 178 and inner wall 132 of compressor housing 40.

Referring to FIG. 2, compressor assembly 90 may include vaneless space 200 extending from outer edges 78 of a rearmost row 32 of compressor blades 26 and vane leading edges 180. A radial extent AR of vaneless space 200 may be selected so that high frequency vibration of vanes 148 caused by pressure wakes generated at vane leading edges 180 may be reduced or eliminated. In particular, the radial extent AR may be selected to be at least 20% of a maximum radius R₂ of compressor blades 26 in rearmost row 32 of compressor impeller 16 to reduce or eliminate high frequency vibrations in compressor blades 26. A larger value of AR may be advantageously selected to further reduce the effect of pressure wakes generated at vane leading edges 180 on compressor blades 26. To minimize an overall volume of compressor stage 12, however, radial extent AR may be selected to range from about 20% to 40% of radius R₂. Selecting the radial extent of vaneless space 200 in this manner may help to reduce or eliminate fatigue failures of compressor blades 26 caused by vibrations induced in compressor blades 26 by pressure wakes generated at vane leading edges 180. Reducing or eliminating the fatigue failures of compressor blades 26 may help extend a useful life of compressor assembly 90.

Referring to FIGS. 3 and 4, tabs 226 may help to prevent rotation of diffuser ring 60 relative to rotational axis 50. Further, washers 244 and fasteners 242 may help attach diffuser ring 60 to volute rear wall 100 of compressor housing 40. Depths of recesses 220 and 239 may be selected so as to maintain an axial gap 234 between tab front face 228 and recess rear face 222 of volute rear wall 100. Axial gaps 234 and radial gaps 236 between tab side surface 232 and recess side surface 224 of recess 220 may help ensure that diffuser ring 60 and tabs 226 may freely expand relative to compressor housing 40 without significantly wearing out tab front face 228, tab rear face 230, and tab side surface 232 during operation of turbocharger 10. In some exemplary embodiments, tabs 226 and diffuser ring 60 may be made out of aluminum, aluminum alloy, or other alloys, which may have a relatively high coefficient of thermal expansion relative to compressor housing 40, which may be made of an iron alloy or other alloys. During operation of turbocharger 10, a temperature of diffuser ring 60 and compressor housing 40 may increase. Diffuser ring 60 and tabs 226 may expand radially and axially to a much larger extent than volute rear wall 100 of compressor housing 40. Thus, tabs 226 may move radially and axially relative to compressor housing 40 numerous times. For example, in one exemplary embodiment, tabs 226 may move radially and axially relative to compressor housing 40 many thousands of times during operation of turbocharger 10. Radial gap 236 may allow tabs 226 to expand freely without interfering with recess side surface 224. Further, axial gap 234 may allow tabs 226 to move relative to recess rear face 222 without causing excessive wear of tabs 226. Thus, tabs 226 may allow diffuser ring 60 to be firmly attached to compressor housing 40, while still allowing relative movement between tabs 226 and recess rear face 222 of recess 220 in volute rear wall 100 caused by differential thermal expansion of diffuser ring 60 and compressor housing 40.

Additionally, when turbocharger 10 with four tabs 226 is mounted on a horizontal surface with the gravitational direction being generally orthogonal to the horizontal surface, first and second diametrical axes 237 and 238 may be positioned symmetrically about the gravitational direction. Positioning first and second diametrical axes 237, 238 in this manner may allow an entire weight of turbocharger 10 to be about equally distributed on each of the four tabs 226. Furthermore, such an arrangement may also allow additional radial loads generated by the operation of turbocharger 10 to be distributed about equally between the four tabs 226.

Referring to FIG. 6, compressor housing assembly 260 may help ensure that bolts 46 are not subjected to bending loads when used to assemble compressor housing 40 and bearing housing 44. As illustrated in FIG. 6, clamping plate 262 may be supported at radial locations by compressor flange lip 280 and flange rear face 114 of bearing housing flange 106. Clamping plate 262 may span compressor flange recess 278. Supporting clamping plate 262 at radially separated locations may allow clamping plate 262 to maintain compressor housing 40 and bearing housing 44 in an assembled configuration even when compressor housing 40 and bearing housing 44 undergo different amounts of axial thermal expansion. Supporting clamping plate 262 on compressor flange lip 280 and bearing housing flange 106 may also allow clamping plate 262 to bend into compressor flange recess 278 as bolts 46 are turned. Bending of clamping plate 262 may help ensure tensile load is generated along a longitudinal axis of bolts 46 while reducing bending loads on bolts 46. Moreover, the tensile load generated in bolts 46 because of bending of clamping plate 262 may help maintain assembly of compressor housing 40 with bearing housing 44 even if bolts become loose during operation of turbocharger 10. Furthermore, because clamping plate 262 applies an axial load to maintain assembly of compressor housing 40 and bearing housing 44, clamping plate 262 may allow compressor flange lip 280 and bearing housing flange 106 to undergo different amounts of radial expansion while still maintaining a clamping load induced by bolts 46.

Referring to FIG. 8, turbine housing assembly 310 may help ensure that bolts 48 are not subjected to bending loads when used to assemble turbine housing 42 and bearing housing 44. As illustrated in FIG. 8, clamping plate 312 may be supported at radial locations by turbine wall lip 336 and bearing housing flange 344. Clamping plate 312 may span turbine flange recess 334. Supporting clamping plate 312 at radially separated locations may allow clamping plate 312 to maintain turbine housing 42 and bearing housing 44 in an assembled configuration even when turbine housing 42 and bearing housing 44 undergo different amounts of axial thermal expansion. Supporting clamping plate 312 on turbine wall lip 336 and bearing housing flange 344 may also allow clamping plate 312 to bend into turbine flange recess 334 as bolts 48 are turned. Bending of clamping plate 312 may help ensure tensile load is generated along a longitudinal axis of bolts 48 while reducing bending loads on bolts 48. Moreover, the tensile load generated in bolts 48 because of bending of clamping plate 312 may help maintain assembly of turbine housing 42 with bearing housing 44 even if bolts become loose during operation of turbocharger 10. Furthermore, because clamping plate 312 applies an axial load to maintain assembly of turbine housing 42 and bearing housing 44, clamping plate 312 may allow turbine wall lip 336 and bearing housing flange 344 to undergo different amounts of radial expansion while still maintaining a clamping load induced by bolts 48.

It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed compressor assembly. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed compressor assembly. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents. 

What is claimed is:
 1. A compressor assembly, comprising: a compressor housing, including an inner wall inclined at a first angle relative to a plane disposed generally orthogonal to a rotational axis of the compressor assembly; a compressor impeller disposed within the compressor housing; a bearing housing attached to the compressor housing, the bearing housing including: a body portion; and a web extending outward from the body portion to a web end, the web being inclined at a second angle relative to the plane; a diffuser ring disposed between the inner wall and the web; and a spring disposed between the web and the diffuser ring, the spring being configured to apply a generally axial load on the diffuser ring.
 2. The compressor assembly of claim 1, wherein the web includes: a ledge disposed between the body portion and the web end; a first web face extending from the body portion to the ledge; and a second web face extending from the ledge to the web end, wherein the diffuser ring is disposed between the second web face and the inner wall.
 3. The compressor assembly of claim 2, wherein the ledge includes: a ledge outer surface extending axially from the first web face to a ledge end disposed between the first web face and a compressor rear end; and a ledge axial face extending radially outward from the ledge end to the second web face.
 4. The compressor assembly of claim 3, wherein the diffuser ring includes: a back plate extending from a back plate leading edge to a back plate trailing edge, wherein the back plate leading edge is disposed adjacent the ledge outer surface, and the back plate is separated from the second web face by a cavity; and a vane extending from the back plate towards the inner wall.
 5. The compressor assembly of claim 4, wherein the vane includes a vane tip configured to abut on the inner wall.
 6. The compressor assembly of claim 5, wherein the back plate includes: a front face disposed opposite the inner wall; a bottom face configured to abut on the ledge outer surface; a rear face separated from the second web face by the cavity; and a recess disposed between the bottom face and the rear face, the recess being located adjacent the ledge outer surface, the recess including: a recess upper face extending axially from the rear face towards the front face; and a recess side face extending between the recess upper face and the bottom face.
 7. The compressor assembly of claim 6, wherein the spring is disposed in the recess between the ledge axial face and the recess side face.
 8. The compressor assembly of claim 7, wherein the spring is a generally annular wave spring having an inner radius larger than a radius of the ledge outer surface.
 9. The compressor assembly of claim 8, wherein the ledge outer surface includes an annular groove, and a seal member is disposed in the annular groove between the ledge outer surface and the bottom face of the back plate.
 10. The compressor assembly of claim 8, wherein the compressor housing includes a volute having a volute rear wall; and the bearing housing includes a bearing housing flange extending radially outward from the web end, the bearing housing flange being configured to be connected to the volute rear wall.
 11. The compressor assembly of claim 10, wherein the volute rear wall has an inner face, and the back plate includes a top face separated from the inner face by a radial gap.
 12. The compressor assembly of claim 1, wherein the first angle is about equal to the second angle.
 13. A diffuser ring comprising: a back plate, including: a front face inclined at a first angle relative to a plane disposed generally orthogonal to a rotational axis; a rear face inclined at a second angle relative to the plane; a top face extending axially from the front face towards the rear face; and a bottom face extending axially from the front face towards the rear face; and a vane extending outward from the front face.
 14. The diffuser ring of claim 13, wherein the front face extends from a back plate leading edge to a back plate trailing edge; and the vane extends from a vane leading edge to a vane trailing edge disposed between the back plate leading edge and the back plate trailing edge.
 15. The diffuser ring of claim 14, further including a recess disposed adjacent the bottom face, the recess including: a recess upper face extending axially from the rear face towards the front face; and a recess side face extending radially inwards from the recess upper face to the bottom face.
 16. The diffuser ring of claim 14, wherein the vane leading edge intersects with the front face at a location disposed between the back plate leading edge and the back plate trailing edge.
 17. A turbocharger, comprising: a turbine housing; a turbine wheel disposed within the turbine housing and configured to be driven by exhaust received from an engine; a compressor housing, including an inner wall inclined at a first angle relative to a plane disposed generally orthogonal to a rotational axis of the turbocharger; a compressor impeller disposed within the compressor housing; a shaft connecting the turbine wheel and the compressor impeller; a bearing housing attached to the compressor housing and the turbine housing, the bearing housing including: a body portion; and a web extending outward from the body portion to a web end, the web being inclined at a second angle relative to the plane; a diffuser ring disposed between the inner wall and the web; and a spring disposed between the web and the diffuser ring, the spring being configured to apply a generally axial load on the diffuser ring.
 18. The turbocharger of claim 17, wherein the web includes: a ledge disposed between the body portion and the web end; a first web face extending from the body portion to the ledge; and a second web face extending from the ledge to the web end, wherein the diffuser ring is disposed between the second web face and the inner wall.
 19. The turbocharger of claim 18, wherein the ledge includes: a ledge outer surface extending axially from the first web face to a ledge end disposed between the first web face and a compressor rear end; and a ledge axial face extending radially outward from the ledge end to the second web face.
 20. The turbocharger of claim 19, wherein the diffuser ring includes: a back plate extending from a back plate leading edge to a back plate trailing edge, wherein the back plate leading edge is disposed adjacent the ledge outer surface, and the back plate is separated from the second web face by a cavity; and a vane extending from the back plate towards the inner wall. 